U.S. patent number 8,337,504 [Application Number 12/879,778] was granted by the patent office on 2012-12-25 for system and method for inserting an implant.
This patent grant is currently assigned to Depuy Products, Inc.. Invention is credited to Gabriel Surma.
United States Patent |
8,337,504 |
Surma |
December 25, 2012 |
System and method for inserting an implant
Abstract
An implant includes a body configured to be implanted at least
partially within a bone canal. The body has a proximal end, a
longitudinal axis and a cavity located at the proximal end. The
cavity is configured to mate with an insertion tool and defines a
cavity axis that is not parallel to the longitudinal axis of the
implant.
Inventors: |
Surma; Gabriel (Winona Lake,
IN) |
Assignee: |
Depuy Products, Inc. (Warsaw,
IN)
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Family
ID: |
38822906 |
Appl.
No.: |
12/879,778 |
Filed: |
September 10, 2010 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20100331994 A1 |
Dec 30, 2010 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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11421972 |
Jun 2, 2006 |
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Current U.S.
Class: |
606/99; 623/22.4;
606/86R |
Current CPC
Class: |
A61F
2/367 (20130101); A61F 2/4607 (20130101); A61F
2002/30354 (20130101); A61F 2250/0026 (20130101); A61F
2002/30322 (20130101); A61F 2002/3625 (20130101); A61F
2002/4628 (20130101); A61F 2220/0033 (20130101); A61F
2002/4062 (20130101); A61F 2002/30367 (20130101); A61F
2/36 (20130101); A61F 2002/305 (20130101); A61F
2/3676 (20130101); A61F 2002/4635 (20130101); A61F
2002/4681 (20130101); A61F 2220/0025 (20130101); A61F
2002/30795 (20130101) |
Current International
Class: |
A61F
2/46 (20060101); A61B 17/58 (20060101); A61B
17/60 (20060101); A61F 2/00 (20060101); A61F
2/36 (20060101) |
Field of
Search: |
;606/99,86R
;623/22.4,20.36 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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450007 |
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Oct 1991 |
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EP |
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2615097 |
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Nov 1988 |
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FR |
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2749501 |
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Dec 1997 |
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FR |
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Other References
US. Appl. No. 11/421,972, Non Final Rejection, Dec. 26, 2008. cited
by other .
U.S. Appl. No. 11/421,972, Non Final Rejection, Dec. 4, 2009. cited
by other .
U.S. Appl. No. 11/421,972, Final Rejection, Jun. 23, 2009. cited by
other .
U.S. Appl. No. 11/421,972, Final Rejection, Jun. 10, 2010. cited by
other .
Learmonth, Ian D.; Conservative Hip Implants; Current Orthopaedics;
(2005) 255-262, vol. 19, Elsevier, www.elsevier.com/locate/cuor.
cited by other .
Santori, F.S. et al; Ultra-Short Stems with Proximal Load Transfer:
Clinical and Radiographic Results at Five-year Follow-up; Hip
International/vol. 15 No. 1 (suppl3) pp. S31-39; Wichtig Editore,
2006. cited by other .
Walker, Peter S., et al; Design Rationale and Dimensional
Considerations for a Femoral Neck Prosthesis; Clinical Orthopaedics
and Related Research; Dec. 2005; pp. 313-319; No. 441 , .COPYRGT.
2005 Lippincott Williams & Wilkins. cited by other.
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Primary Examiner: Truong; Kevin T
Assistant Examiner: Bates; David
Claims
The invention claimed is:
1. A method of implanting an implant at least partially within a
femur, the femur having a femoral axis, comprising the steps of:
handling a system that includes: an implant comprising a body, the
body having a proximal end, a distal end, a longitudinal axis and a
cavity located at the proximal end, wherein the cavity defines a
cavity axis that is not parallel to the longitudinal axis of the
implant, and a tool for assisting in the implantation of the
implant comprising a shaft having a distal end configured to mate
with the cavity and a proximal end, the proximal end including a
strike plate attached thereto; creating a void in the femur, the
void being located medial of the greater trochanter; introducing
the distal end of the implant into the void, whereat the
longitudinal axis of the implant is not aligned with the femoral
axis; engaging the distal end of the tool into the cavity of the
implant; striking the strike plate to thereby rotate the
longitudinal axis of the implant toward the femoral axis until the
longitudinal axis of the implant is substantially aligned with the
femoral axis; and disengaging the distal end of the tool from the
cavity of the implant; wherein the implant has a stem extending
from the proximal end, the stem extending from the femur when the
implant is substantially aligned with the femoral axis; and wherein
the stem is configured to receive a prosthetic femoral head.
2. The method of claim 1, wherein the handling step comprises
handling a tool that has a distal portion that includes a
cantilevered spring arm that extends from the distal portion, and
the arm being configured to frictionally engage the cavity of the
implant when at least partially disposed therein, and wherein the
engaging step comprises engaging the arm with the cavity.
3. The method of claim 2, wherein the handling step comprises
handling an implant that includes a dimple within the cavity, and
handling a tool that includes a raised surface on a distal end of
the cantilevered spring arm configured to at least partially engage
the dimple when the distal end of the tool is engaged with the
cavity, and wherein the engaging step comprises engaging the raised
surface with the dimple.
4. The method of claim 3, wherein the cantilevered spring arm and
the cavity of the implant are configured to permit disengagement of
the tool and the implant when a force ranging from approximately
one-quarter of a pound to five pounds is exerted proximally along
the longitudinal axis of the tool.
5. The method of claim 2, wherein the creating step includes the
step of creating a void by following a path around the medial curve
of the femur and under the greater trochanter.
6. The method of claim 5, wherein the creating step includes the
step of broaching around the medial curve of the femur and under
the greater trochanter.
7. The method of claim 6, wherein the greater trochanter is
substantially spared.
8. The method of claim 1, wherein the width of the implant
increases from the distal end to the proximal end.
9. The method of claim 8, wherein the widest aspect of the implant
is at least twice the width of the distal end of the implant.
10. The method of claim 1, wherein the implant has opposing sides
that form at least a portion of the distal end, and the opposing
sides diverge away from the longitudinal axis from the distal end.
Description
This invention relates to a method of and system for implanting an
implant, more particularly implanting a hip implant at least
partially within the femoral canal.
Orthopaedic surgeons, as with other specialties, have been driven
to perform their surgery through smaller and smaller incisions in
an attempt to minimize damage to tissue that surrounds the surgical
site, to thereby decrease blood loss and recovery time. In
orthopaedics, particularly, it is recognized that sparing a
patient's bone is preferred whenever possible during surgery. In
hip replacement surgery, a surgeon can attempt to spare the upper
part of the femur (greater trochanter) by using a small incision
surgical technique that employs a short hip implant.
An issue that occurs during this surgery is the difficulty in using
an insertion feature of the implant that is positioned on the
lateral-superior aspect of the implant. The feature is located at
this position due to the compromise between accessibility of the
feature and the mechanical strength requirements imposed on the
implant. Currently available straight, in-line impactors and
implant insertion features are positioned coincident with or
parallel to the long (or longitudinal) axis of the implant. When
the surgeon attempts to finally seat the implant using the
insertion feature, the position of the insertion feature can cause
the impactor to interfere with the mass of the greater trochanter.
As a result of this difficulty, the surgeon may not completely seat
the implant, thereby compromising the biomechanics of the joint
space and potentially leading to implant subsidence and/or
dislocation.
BRIEF SUMMARY OF THE INVENTION
The present invention addresses the shortcomings of the prior art
by providing an improved method of and system for inserting and
impacting an implant.
The preferred embodiment of the implant system allows the insertion
of a short implant using the `around the corner` surgical
technique. This technique aims to minimize the damage to the
greater trochanter by broaching around the medial curve of the
femur and under the greater trochanter. The insertion feature
located on the implant is designed to mate with the
inserter/impactor tool in a way that allows for rotational control
of the implant but is also removable using a low force. The system
addresses the problem of greater trochanter impingement by both
angling the insertion feature with respect to the long axis of the
implant and curving the impactor to travel around the greater
trochanter during the "around the corner" insertion motion.
While the issue of navigating a short implant in a hip procedure is
described in some detail below, it is contemplated that the implant
system can be used in any method where an implant needs to be
inserted or positioned in a non-axial fashion. For example, a
similar method and system can be used to implant humeral implants.
The invention is also not necessarily limited to implantation of
long-bone implants. The system can be employed wherever the
insertion path of the implant benefits from being out of axis of
the ultimate location of the implant.
According to the present invention a short hip implant includes a
body configured to be implanted at least partially within the
femoral canal. The body has a proximal end, a longitudinal axis and
a cavity located at the proximal end. The cavity is configured to
mate with an insertion tool, and defines a cavity axis that is not
parallel to the longitudinal axis of the implant.
According to another aspect of the present invention a hip implant
system includes a short hip implant having a body with a proximal
end, a longitudinal axis, and a cavity. The cavity has a cavity
axis that is not parallel to the longitudinal axis. The system also
includes a tool for assisting in the implantation of the implant
that has a distal end configured to mate with the cavity.
According to another aspect of the present invention a hip implant
system includes a short hip implant having a body with a proximal
end, a longitudinal axis, and a cavity. The system also includes a
tool for assisting in the implantation of the implant that has a
distal end configured to mate with the cavity. The distal end has
an axis that is not parallel to the longitudinal axis of the body
when the tool is mated with the implant.
A method of implanting a short implant at least partially within a
bone, wherein the bone has an axis, is also provided. The method
includes the steps of (a) providing a system including an implant
having a body with a proximal end, a distal end, a longitudinal
axis and a cavity located at the proximal end, the cavity being
configured to mate with an insertion tool and defining a cavity
axis that is not parallel to the longitudinal axis of the implant,
and a tool for assisting in the implantation of the implant, the
tool including a shaft having a distal end configured to mate with
the cavity and a proximal end, the proximal end including a strike
plate attached thereto; (b) creating a void in the bone; (c)
introducing the distal end of the short implant into the void,
whereat the longitudinal axis of the implant is not aligned with
the bone axis; (d) engaging the distal end of the tool into the
cavity of the implant; (e) striking the strike plate to thereby
rotate the longitudinal axis of the implant toward the bone axis
until the longitudinal axis of the implant is substantially aligned
with the bone axis; and (f) disengaging the distal end of the tool
from the cavity of the implant.
A method of implanting an implant at least partially within tissue,
wherein the tissue includes an implant target position having a
target axis and a tissue feature that intersects the target axis,
is also provided. The method includes the steps of (a) providing a
system including an implant that has (i) a body, the body having a
proximal end, a distal end, a longitudinal axis and a cavity
located at the proximal end, wherein the cavity defines a cavity
axis that is not parallel to the longitudinal axis of the implant,
and (ii) a tool for assisting in the implantation of the implant
comprising a shaft having a distal end configured to mate with the
cavity and a proximal end; (b) creating a pathway from a tissue
surface to a target position within the tissue; (c) inserting the
distal end of the implant into the pathway; (d) engaging the distal
end of the tool with the cavity of the implant; (e) manipulating
the tool to move the implant to the target position without
impinging on the tissue feature; and (f) disengaging the distal end
of the tool from the cavity of the implant.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features, advantages and benefits will be made
apparent through the following descriptions and accompanying
figures, where like reference numerals refer to the same features
across the various drawings.
FIG. 1 shows a side view of a short hip implant engaged with a tool
for assisting in the implant of the hip implant according to one
embodiment of the invention;
FIG. 2 shows a to scale, cross-sectional view of the tool of FIG.
1;
FIGS. 3A and 3B show a close-up view of the distal end of the tool
of FIG. 1, respectively, disengaged and engaged with the proximal
end of the implant of FIG. 2;
FIG. 4 shows a schematic view of the implant being inserted into
the femur in three stages according to one embodiment of the
invention; and
FIGS. 5A-5C show a schematic view of the implant being inserted
into the femoral canal in three stages according to one embodiment
of the invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings, FIG. 1 shows a hip implant system
according to the invention, generally referred to as reference
numeral 10. The hip implant system includes a short hip implant 20
and a tool 30 for assisting in the implantation of implant. Implant
20 includes a distal end 21, a proximal end 22, a stem 23 extending
from proximal end 22, and an insertion cavity 24 formed in proximal
end 22 (FIG. 3A). Tool 30 has a shaft 31, having a proximal end 32
and a distal end 40, a strike plate 33 connected to proximal end 32
and grip 34 extended from a medial portion 39 of shaft 31. Tool 30
is approximately 25 cm in length.
FIG. 1 depicts distal end 40 of tool 30 at least partially disposed
in cavity 24 of implant 10. Distal end 40 is configured to mate
with cavity 24 such that implant 10 may be securely held during the
implant procedure, which as is described in more detail below,
includes the steps of inserting and impacting via a "round the
corner" surgical technique.
Referring to FIG. 2, tool 30 is shown in cross-section. A top
surface 35 of strike plate 33 is rounded to permit plate 33 to be
impacted at multiple locations as implant 10 is inserted into its
ultimate position. As is described in greater detail below, the
surgical technique for one embodiment of the invention requires a
"round the corner" approach that permits the implant to be inserted
while avoiding contact with the greater trochanter. To facilitate
this requirement, strike plate 33 is rounded at a medial end 33a
allowing impaction of implant 20 in a lateral direction at an
oblique angle "around the corner" to a position inline with the
axis of the femur. Further impaction can then be performed on a
flat portion at lateral end 33b of plate 33 to seat implant 20 to
the correct depth within the proximal femur.
Strike plate 33 has a counter-sunk bore 36 that extends from top
surface 35 distally toward shaft 31 of tool 30. Bore 36 is
configured to accept a portion of an alignment member 50 (FIG. 4).
In a preferred embodiment, bore 36 is approximately 9 mm. The
interface between tool 30 and alignment member 50 is preferably a
clearance fit, which allows for easy operation of the alignment
member and encourages intra-operative use of the alignment member,
as its use consumes no additional time during surgery. The axis of
bore 36 preferably is designed to be parallel with the implant axis
when implant 10 is finally positioned in situ.
Grip 34 is fixed relative to shaft 31 and is shaped such that it
complements the shape of the instrument body and provides the
surgeon comfort and control when gripped during the method. Shaft
31 is preferably in the shape of an s-curve, so as to increase
visualisation of the wound while clearing patient anatomy. That is,
distal end 40 is not aligned with proximal portion 32 so as to
provide the surgeon with a clear view of distal end 40 so as make
the use of smaller incisions more practicable.
Referring to FIGS. 3A and 3B, the insertion feature is shown in
detail in a disengaged position and an engaged position,
respectively. Only the proximal portion 22 of implant 20 is
depicted in FIGS. 3A and 3B. In accordance with the invention,
cavity 24 has an axis C that is not aligned with the longitudinal
axis L of implant 10. In a preferred embodiment, axis C is offset
from longitudinal axis L by angle A, which ranges from 5 degrees to
55 degrees. More preferably, angle A ranges from 15 to 45 degrees.
Most preferably angle A is about 40 degrees. Distal portion 25 of
cavity 24 is preferably circular in cross section and preferably is
approximately 9 mm in diameter. Cavity 24 includes a slot 26 that
communicates with distal portion 25 and a dimple 27, each
configured to accept features of insertion/impact tool 30. In a
preferred embodiment, the distance from the center of dimple 27 to
the bottom of cavity 24 is approximately 13 mm. Slot 26 is
preferably 3.5 mm in width and need not run the full depth of the
cavity.
Distal end 40 of tool 30 includes a distal tip 41 that is circular
in cross-section and configured to engage distal portion 25 of
cavity 24. Distal tip 41 is designed to transmit the impaction
force from strike plate 33 to implant 20. Distal end 40 also
includes a rib 42 which is configured to engage slot 26 of cavity
24. Rib 42 permits the surgeon to control the orientation of
implant 10 as it permits implant 20 to have only one orientation
with respect to insert/impactor tool 30 during operation. Distal
end 40 also includes a cantilevered spring arm 43, which preferably
extends from distal end 40 at a location circumferentially
displaced from the location of rib 42. In a most preferred
embodiment, rib 42 is located on the opposite side of distal end 40
from arm 43. Arm 43 includes a male feature or protrusion 44, which
is preferably a spherical protrusion, designed to frictionally
engage female feature or dimple 27 of implant 20. Frictional
engagement of protrusion 44 with dimple 27 ensures that the implant
remains attached while navigating through soft tissues. This design
of attachment ensures that tool (or instrument) 30 is easily
removed from implant 20 following final impaction. The spring arm
43 is designed so that at least one-quarter pound is required to be
exerted to remove distal portion 40 from implant 20.
Referring to FIGS. 4 and 5A-5C, the described implant system allows
the insertion of a short implant using the `around the corner`
surgical technique. The goal of this technique is to minimize the
damage to the greater trochanter of the hip by broaching around the
medial curve of the femur M and under the greater trochanter GT.
The invention addresses the problem of greater trochanter
impingement by both angling the insertion feature with respect to
the long axis of the implant L and curving the impactor to travel
around the greater trochanter GT during the "around the corner"
insertion motion.
System 10 is used as follows. The surgeon controls implant 20 with
tool 30. Implant 20 is held in an engaged position with tool 30 by
spring arm 43, which includes a male feature 44 that is disposed in
a corresponding female feature 27 of implant 20. The surgeon
controls the orientation of implant 20 by rib 42, which engages
slot 26 of implant 20. Once a void is created in bone by broaching
or another method known in the art, distal end 21 of implant 20 is
positioned at the opening in the void. Referring to FIG. 5A, tool
30 can be engaged with implant 20 prior to or at this stage in the
method.
When the surgeon desires to impact strike plate 33 to encourage
implant 20 to assume the correct implant position, the surgeon
engages distal end 40 of tool 30 with cavity 26 of implant 20.
Referring to FIG. 5B, the surgeon then repeatedly impacts strike
plate 33 at proximal end 32 of tool 30. As the surgeon impacts tool
30, implant 20 rotates about the medial curve of the femur M and
under the greater trochanter GT as shown in FIGS. 5A-5C and in
shadow FIG. 4. As implant 20 rotates, the longitudinal axis L of
implant 20 rotates toward femoral axis F. The implant is correctly
positioned when the longitudinal axis L of implant is substantially
aligned with femoral axis F.
Referring to FIG. 4, once the surgeon believes that implant 20 has
achieved its optimal position in the proximal femur, the position
of implant 20 can be assessed by attaching alignment member 50 to
tool 30 via the bore 36 in the plate 33. Member 50 includes a first
arm 51 that engages with bore 36, a second arm 52 that extends at a
right angle from first aim 51 and a third arm that extends at a
right angle from second arm 52 in a direction parallel to first arm
51. In this way, third arm 53 can be aligned with the femoral axis
of the leg to visually confirm that implant 20 is in the correct
position. If implant 20 is misaligned, the surgeon can continue to
impact plate 33 to correct the alignment or exert a torsional force
on tool 30 to correct the varus/valgus orientation, e.g.
Removal of tool 30 from implant 20 is performed by pulling
proximally on the proximal end of tool 30 with a force great enough
to overcome spring arm 43. The force can be designed to range from
one-quarter pound to five pounds. Excessive force is not required
and as such the position of implant 20 in the proximal femur is not
altered.
While the issue of navigating a short implant in a hip procedure is
described in some detail herein, it is contemplated that the
implant system can be used in any method where an implant needs to
be inserted or positioned in a non-axial fashion. For example, a
similar method and system can be used to implant humeral implants.
Moreover, the invention is not necessarily limited to implantation
of long-bone implants. The system can be employed wherever the
insertion path of the implant benefits from being out of axis of
the ultimate location of the implant.
System 10 of the invention, for example, can be used to navigate an
implant to final position without impingement on defined bone
feature or specific tissue structure that a surgeon wishes to
spare, wherein the bone feature or specific tissue structure is
located in a position that intersects an implant axis at a location
proximal to the final position of the implant. Typically, in this
situation, an implant would follow an axial path to its final
position, one aligned with the implant axis. Utilizing the system
of the invention, the surgeon can retain the bone feature that
would otherwise need to be removed or at least damaged in providing
a path for the implant, by inserting the implant along a non-axial
path. In the preferred embodiment, implant 20 is navigated to a
position wherein implant longitudinal axis L is aligned with
femoral axis F, but the path taken is non-axial. That is, rather
than delivering implant 20 by impacting implant 20 along an axis
parallel (if not coincident) with implant axis L, implant 20 is
impacted along a cavity axis C which is not parallel to implant
longitudinal axis L. As a result, the path taken by implant 20 is
curved rather than straight, and the greater trochanter bone, that
would otherwise be sacrificed or at least damaged by contact with
the implant if implant 20 took an axial path to its final position,
is spared any damage. This same concept can be used to spare other
bone features by the surgeon.
Specific construction details that are not shown are believed to be
within the purview of those of ordinary skill in the art. The
present invention has been described herein with reference to
certain preferred embodiments. These embodiments are offered as
illustrative, and not limiting, of the scope of the invention.
Certain modifications or alterations may be apparent to those
skilled in the art without departing from the scope of the
invention, which is defined by the appended claims.
* * * * *
References